1. Field of the Invention
This invention relates to an automatic branch cut-off device. More particularly, the invention relates to an automatic branch cut-off device which is attached onto the trunk of a tree at its base, and which is automatically driven upwardly in order to cut off the lower branches of the tree while the machine is in a revolving helical type of movement. After the branches have been removed, the direction of movement of the mechanism can be changed by a transfer clutch and the device driven downwardly.
2. Description of the Prior Art
There are basically two situations where the lower branches of a tree are to be removed. One situation is where they are obstructive to the removal of the tree when the tree is being cut down and, consequently, the lower branches are cut off prior to the tree being cut down. This is called "disbranching". The second situation is where the lower branches may be cut off during a period of growth. This is called "pruning", and it is done in order that the tree may grow straight and without any knots. The former situation of disbranching is concerned with trees of a relatively large size, while pruning is concerned with trees of a generally small size.
Previously, cutting the lower branches off of a tree was often performed by an individual who had to climb the tree in order to cut the branches, and use a saw, hatchet or the like for the cutting operation. In either disbranching or pruning, cutting was carried out either by a machine tool or was done manually.
Conventional devices and methods for cutting off lower tree branches as discussed above contained several disadvantages. In manually operated cutting, the possibility exists that cut branches may fall and injure the operator. In addition, it is usually not possible to cut off the lower branches at a height sufficient to obtain the desired results. Prior art pruning methods are undesirable, especially when pruning branches during a growth period.
Accordingly, it has become necessary to develop a mechanical device which would prove suitable and which would eliminate the disadvantages inherent in the prior art devices. One attempt to produce such a device is shown in Japanese patent publication no. 27370/1970. The invention disclosed in this application relates to a device which is driven upwardly on a tree trunk by means of a guide pulley which ascends and descends the tree trunk helically. The ascendant speed is varied by means of a speed change gear in order to cut off the branches. However, this device is unable to operate if the tree surface is not uniformly smooth. Also, it does not contain a means for driving the device down after the branches are cut off the tree.
The inventor of the subject invention has developed an invention which is directed to an automatic branch cut-off device which overcomes the above-noted disadvantages. As a result of extensive research, this present invention has been developed, which improves its elevating means with a simplified mechanism.